Effect of different intraoral scanners and scanbody splinting on accuracy of scanning implant-supported full arch fixed prosthesis

Scan accuracy of wireless intraoral scanners while digitizing a combined scan body-healing abutment system: Scan accuracy of wireless scanners

OBJECTIVES

To investigate the accuracy (trueness and precision) of wireless and wired intraoral scanners (IOSs) when scanning an implant with the combined healing abutment-scan body (CHA-SB) system.

METHODS

A partially edentulous mandibular model with a CHA-SB at the right first molar site was digitized with 2 wireless (NeoScan 2000 (NW) and TRIOS 4 wireless (T4W)) and 2 wired (NeoScan 1000 (N) and TRIOS 4 wired (T4)) IOSs 44 times in total (n=11). The reference scan file was generated by digitizing the same master model and CHA-SB with an industrial-grade optical scanner. All files were imported into a metrology-grade analysis software program to evaluate the surface (root mean square, RMS), linear, and angular deviations of the top part of the SB. The average deviation values defined the precision of the scans. The data were statistically analyzed (α = 0.05).

RESULTS

IOS type affected the surface and angular deviations and the precision (linear deviations on the x-axis) of the scans (p ≤ 0.043). T4W had lower RMS than N and T4 (p ≤ 0.031). T4 had higher angular deviations than N on the XZ plane and had the lowest angular deviations on the YZ plane (p ≤ 0.011). T4W scans had higher precision than N scans (p = 0.024).

CONCLUSION

Despite some differences in the trueness or precision of scans, tested IOSs mostly enabled similar scan accuracy. Regardless of the IOS, the implant scans had a tendency to tilt mesiobuccally, which can be considered clinically small.

CLINICAL SIGNIFICANCE

Tested wireless intraoral scanners may be suitable alternatives to their wired counterparts while digitizing an implant with a combined healing abutment-scan body system in the posterior region. However, the crowns fabricated from tested scans might require buccal, mesial, and occlusal surface veneering and distal surface adjustments.

Does intra-oral scan improve the impression accuracy of full-arch implant-supported prostheses: A systematic review and meta-analysis

OBJECTIVES

The present study aimed to systematically review the studies comparing the accuracy of intraoral scan (IOS) and conventional implant impressions (CI) in completely edentulous patients.

MATERIALS AND METHODS

Electronic searches were performed in PubMed, Embase and Cochrane CENTRAL up to December 1, 2023. Clinical studies and in vitro studies reporting the accuracy of digital full arch impressions were included. The primary outcome is the 3-dimensional deviations between the study reference models. A risk of bias assessment was performed for clinical studies. A stratified meta-analysis and a single-armed meta-analysis were conducted.

RESULTS

A total of 49 studies were included, with 8 clinical studies and 41 in vitro studies. For comparison between IOS and conventional impressions, studies were categorized into two groups based on the different measurement methods employed: RMS and CMM. In studies using RMS, the result favored the IOS in the unparalleled situation with the mean difference of -99.29 μm (95% CI: [-141.38, -57.19], I2 = 81%), while the result was opposite with the mean difference of 13.62 μm (95% CI: [10.97, 16.28], I2 = 26%) when implants were paralleled. For different brands of IOS, the accuracy ranged from 76.11 μm (95% CI: [42.36, 109.86]) to 158.63 μm (95% CI: [-14.68, 331.93]).

CONCLUSIONS

Accuracy of intraoral scan is clinically acceptable in edentulous arches, especially for unparalleled implants. More clinical studies are needed to verify the present finding.

Intraoral scanners in implant prosthodontics. A narrative review

OBJECTIVES

To review the developments in intraoral scanner (IOS) technologies applied in implant prosthodontics, emphasizing their influence on the accuracy of digital impressions, occlusal registrations, and the fit of implant-supported restorations.

DATA

A collection of published articles related to implant prosthodontics, the accuracy of digital impressions, occlusal registration, and the fit of implant-supported fixed restorations.

SOURCES

Three search engines were selected: Medline/PubMed, EBSCO, and Cochrane. A manual search was also conducted.

STUDY SELECTION

A literature search screened relevant databases and journals for studies on IOS applications in digital implant prosthodontic workflows from Dec 2018 to Dec 2023. Inclusion criteria encompassed randomized control trials, clinical trials, case series, and in vitro research focused on the use of IOS in digital implant prosthodontics.

CONCLUSIONS

The increased utilization of digital dental technologies has led to significant integration of digital implant prosthodontic workflows into clinicians' clinical practice. Several variables affect the accuracy of digital impressions generated by IOS. Generally, the prevailing opinion in academic papers is that digital workflows are suitable for addressing short-span implant-supported restorations. However, when it comes to long-span defects, the accuracy of digital workflows is still a matter of debate. Digital bite registration is an integral part of the workflow. It depends mainly on the defect size and location, scan strategy, anatomical tooth variations, overbite and other factors. The overall fit of digitally prefabricated implant restorations comprises of proximal, occlusal contacts and how accurately the restoration connects with implants. Research methodologies need standardization for further validation.

CLINICAL SIGNIFICANCE

In clinical practice, it is essential to have a thorough and up-to-date comprehension of various factors that can affect the accuracy of digital impressions and the fit of the final prosthesis in implant prosthodontics.

Influence of different scan body design features and intraoral scanners on the congruence between scan body meshes and library files: An in vitro study

STATEMENT OF PROBLEM

Implant scan bodies (ISBs) present with a variety of features, including diverse design geometries and manufacturing materials. How these features influence the congruence between the clinically obtained mesh file and the software-based library file of the scan body during the alignment stage within the computer-aided design (CAD) software program is unclear. It is also uncertain how these features influence the scanning accuracy of different scanners.

PURPOSE

The purpose of this in vitro study was to investigate how various scan body shapes manufactured from different materials influence the scanning accuracy of 6 intraoral scanners (IOSs) and 1 desktop scanner.

MATERIAL AND METHODS

A 3-dimensionally (3D) printed cast fitted with 4 different implant analogs and their corresponding scan bodies (Straumann Cares RN Mono; Straumann, MIS V3 SP; MIS, Paltop SP; Paltop and TV70; TRI) was scanned using 6 intraoral scanners (Primescan; Dentsply Sirona, TRIOS 3; 3Shape A/S, TRIOS 5; 3Shape A/S, Medit i-700; Medit, Fussen S6000; Fussen, and Runyes 3DS; Runyes) and 1 desktop scanner (7series; Dental Wings). A metrology mesh comparison software program was used for analysis. Inferences were drawn using a univariate repeated measures 2-way ANOVA. Post hoc analysis was conducted with pairwise Bonferroni tests (α=.05).

RESULTS

A significant 2-way interaction was found between scanner model and scan body model, (F [5.518, 49.659]=36.251, P<.001). The mean absolute deviation for the different scanners ranged between 21 µm and 35 µm across all scan bodies, but the model of the scan body influenced the deviation of the scanner. The mean absolute deviation for the different scan bodies ranged from 19 µm to 46 µm across all scanners, but the model of the scanner influenced the deviation of the scan body.

CONCLUSIONS

Regarding implant scan body features, a design with a less complex shape and fewer sharp line angles and a design with a cylindrical shape exhibited statistically significantly higher congruence between the clinical mesh and the software library files. Regarding intraoral scanners, Primescan had a statistically significantly lower mean absolute deviation compared with that of the other scanners across all scan bodies tested.

Novel complete-arch pillar system (CAPS) to register implant position and maxillomandibular relationship in one single visit

OBJECTIVES

This article presents a novel complete-arch pillar system (CAPS) to register implant position and maxillomandibular relationship in one single visit for implant-supported fixed complete dental prostheses (IFCDPs).

MATERIAL AND METHODS

The novel system presents a 3-unit toolset comprising intraoral scan bodies (ISBs), lateral pillar attachments (LPAs) and occlusal pillar attachments (OPAs). A 2-stage single visit workflow by an intraoral scanner (Trios 5) was introduced. The first stage "Screw-Scan-Done" was used to describe complete-arch intraoral implant scanning using LPAs. The second stage "Screw-Occlude-Done" involved virtual occlusal recording using OPAs. Two patients with one single edentulous arch were selected for this study. In the first patient, 6 bone level implants (Bone Level Tapered, Straumann) were placed in the edentulous maxilla at positions 12, 14, 16, 22, 24 and 26. In the second patient, 4 bone level implants (NobelActive CC, Nobel Biocare) were placed in the edentulous mandible at positions 32, 35, 42 and 45. A CAD-CAM procedure was initiated with the acquired IOS data to fabricate an interim IFCDP at the same day. Periapical radiographs were obtained of the implant-prosthetic connection of the definitive IFCDPs to verify the passive fit. Metrology software (Geomagic Qualify, 3D Systems - Matlab, Mathworks) was used to assess the implant analogs position in the 3D-printed casts used for fabricating the definitive IFCDPs. A quantitative occlusal relationship analysis was performed with IOS.

RESULTS

Radiographic examination revealed no gaps at implant-prosthetic connection of the definitive IFCDPs. The 3D-printed casts showed an overall average distance deviation within the clinically acceptable range of errors of 150 µm. Quantitative occlusal relationship analysis with IOS showed well-distributed contacts.

CONCLUSION

Within the limitations of this study, the following conclusions can be drawn: (1) A 3-unit toolset with ISBs, LPAs and OPAs allows to register the implant position and maxillomandibular relationship in one single visit; (2) the 2-stage clinical workflow with the CAPS system facilitates the IOS data acquisition for fabrication of an interim IFCDP at the same day; (3) a passive fit was demonstrated for the interim and the definitive IFCDPs.

CLINICAL SIGNIFICANCE

The CAPS system can help clinicians to register the implant position and the maxillomandibular relationship in one single visit for the fabrication of an IFCDP.

Obtaining more accurate complete arch implant digital scans with the aid of a geometric pattern: A dental technique

A technique to obtain more accurate complete arch implant digital scans and virtual casts is described. In order to obtain complete arch implant digital scans with greater accuracy, short-span intraoral digital scans are superimposed with the aid of a geometric pattern. Therefore, the technique takes advantage of the accuracy of intraoral scanners to obtain digital scans of reduced spans. Two virtual designs of the geometric pattern have been made available online: one for maxillary arches and one for mandibular arches. From these virtual designs, new virtual designs of geometric patterns of different sizes and shapes can be created to better fit different arch forms and implant positions.

Improving the accuracy of complete arch implant digital scans by using auxiliary clips for intraoral scan bodies: A dental technique

A technique to improve the accuracy of complete arch implant intraoral digital scans and the accuracy of their virtual casts is described. Obtaining accurate complete arch implant intraoral digital scans with an intraoral scanner is challenging because of the smooth and movable tissues of edentulous areas. The described technique uses auxiliary clips attached to intraoral scan bodies to cover interimplant edentulous spans with immobile tooth-like geometric references that are more favorable for intraoral scanning. The technique is designed to be user friendly and compatible with any intraoral scanner.

Improving the accuracy of complete arch implant intraoral digital scans by using horizontal scan bodies with occlusal geometry: A dental technique

A technique to improve the accuracy of complete arch implant intraoral digital scans and to obtain more accurate virtual casts with them is described. First, 2 complete arch intraoral digital scans were obtained with an intraoral scanner: a multiunit abutment digital scan and an implant digital scan with reusable horizontal intraoral scan bodies (ISBs) placed on the implants. These were previously created by combining the conventional ISBs compatible with the patient's implants with extensional structures with occlusal geometry. Once the digital scans had been acquired, the position of the implants was obtained by superimposing a virtual design of the conventional ISB onto each horizontal ISB of the complete arch implant digital scan. Finally, the virtual cast was obtained by superimposing the complete arch multiunit abutment digital scan on the complete arch implant digital scan.